package org.bouncycastle.crypto.engines;

import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.params.KeyParameter;

/**
 * a class that provides a basic DES engine.
 */
public class DESEngine implements BlockCipher {
    protected static final int BLOCK_SIZE = 8;

    private int[] workingKey = null;

    /**
     * standard constructor.
     */
    public DESEngine() {
    }

    /**
     * initialise a DES cipher.
     * 
     * @param encrypting
     *            whether or not we are for encryption.
     * @param params
     *            the parameters required to set up the cipher.
     * @exception IllegalArgumentException
     *                if the params argument is inappropriate.
     */
    public void init(boolean encrypting, CipherParameters params) {
        if (params instanceof KeyParameter) {
            if (((KeyParameter) params).getKey().length > 8) {
                throw new IllegalArgumentException(
                        "DES key too long - should be 8 bytes");
            }

            workingKey = generateWorkingKey(encrypting,
                    ((KeyParameter) params).getKey());

            return;
        }

        throw new IllegalArgumentException(
                "invalid parameter passed to DES init - "
                        + params.getClass().getName());
    }

    public String getAlgorithmName() {
        return "DES";
    }

    public int getBlockSize() {
        return BLOCK_SIZE;
    }

    public int processBlock(byte[] in, int inOff, byte[] out, int outOff) {
        if (workingKey == null) {
            throw new IllegalStateException("DES engine not initialised");
        }

        if ((inOff + BLOCK_SIZE) > in.length) {
            throw new DataLengthException("input buffer too short");
        }

        if ((outOff + BLOCK_SIZE) > out.length) {
            throw new DataLengthException("output buffer too short");
        }

        desFunc(workingKey, in, inOff, out, outOff);

        return BLOCK_SIZE;
    }

    public void reset() {
    }

    /**
     * what follows is mainly taken from "Applied Cryptography", by Bruce
     * Schneier, however it also bears great resemblance to Richard
     * Outerbridge's D3DES...
     */

    // private static final short[] Df_Key =
    // {
    // 0x01,0x23,0x45,0x67,0x89,0xab,0xcd,0xef,
    // 0xfe,0xdc,0xba,0x98,0x76,0x54,0x32,0x10,
    // 0x89,0xab,0xcd,0xef,0x01,0x23,0x45,0x67
    // };

    private static final short[] bytebit = { 0200, 0100, 040, 020, 010, 04, 02,
            01 };

    private static final int[] bigbyte = { 0x800000, 0x400000, 0x200000,
            0x100000, 0x80000, 0x40000, 0x20000, 0x10000, 0x8000, 0x4000,
            0x2000, 0x1000, 0x800, 0x400, 0x200, 0x100, 0x80, 0x40, 0x20, 0x10,
            0x8, 0x4, 0x2, 0x1 };

    /*
     * Use the key schedule specified in the Standard (ANSI X3.92-1981).
     */

    private static final byte[] pc1 = { 56, 48, 40, 32, 24, 16, 8, 0, 57, 49,
            41, 33, 25, 17, 9, 1, 58, 50, 42, 34, 26, 18, 10, 2, 59, 51, 43,
            35, 62, 54, 46, 38, 30, 22, 14, 6, 61, 53, 45, 37, 29, 21, 13, 5,
            60, 52, 44, 36, 28, 20, 12, 4, 27, 19, 11, 3 };

    private static final byte[] totrot = { 1, 2, 4, 6, 8, 10, 12, 14, 15, 17,
            19, 21, 23, 25, 27, 28 };

    private static final byte[] pc2 = { 13, 16, 10, 23, 0, 4, 2, 27, 14, 5, 20,
            9, 22, 18, 11, 3, 25, 7, 15, 6, 26, 19, 12, 1, 40, 51, 30, 36, 46,
            54, 29, 39, 50, 44, 32, 47, 43, 48, 38, 55, 33, 52, 45, 41, 49, 35,
            28, 31 };

    private static final int[] SP1 = { 0x01010400, 0x00000000, 0x00010000,
            0x01010404, 0x01010004, 0x00010404, 0x00000004, 0x00010000,
            0x00000400, 0x01010400, 0x01010404, 0x00000400, 0x01000404,
            0x01010004, 0x01000000, 0x00000004, 0x00000404, 0x01000400,
            0x01000400, 0x00010400, 0x00010400, 0x01010000, 0x01010000,
            0x01000404, 0x00010004, 0x01000004, 0x01000004, 0x00010004,
            0x00000000, 0x00000404, 0x00010404, 0x01000000, 0x00010000,
            0x01010404, 0x00000004, 0x01010000, 0x01010400, 0x01000000,
            0x01000000, 0x00000400, 0x01010004, 0x00010000, 0x00010400,
            0x01000004, 0x00000400, 0x00000004, 0x01000404, 0x00010404,
            0x01010404, 0x00010004, 0x01010000, 0x01000404, 0x01000004,
            0x00000404, 0x00010404, 0x01010400, 0x00000404, 0x01000400,
            0x01000400, 0x00000000, 0x00010004, 0x00010400, 0x00000000,
            0x01010004 };

    private static final int[] SP2 = { 0x80108020, 0x80008000, 0x00008000,
            0x00108020, 0x00100000, 0x00000020, 0x80100020, 0x80008020,
            0x80000020, 0x80108020, 0x80108000, 0x80000000, 0x80008000,
            0x00100000, 0x00000020, 0x80100020, 0x00108000, 0x00100020,
            0x80008020, 0x00000000, 0x80000000, 0x00008000, 0x00108020,
            0x80100000, 0x00100020, 0x80000020, 0x00000000, 0x00108000,
            0x00008020, 0x80108000, 0x80100000, 0x00008020, 0x00000000,
            0x00108020, 0x80100020, 0x00100000, 0x80008020, 0x80100000,
            0x80108000, 0x00008000, 0x80100000, 0x80008000, 0x00000020,
            0x80108020, 0x00108020, 0x00000020, 0x00008000, 0x80000000,
            0x00008020, 0x80108000, 0x00100000, 0x80000020, 0x00100020,
            0x80008020, 0x80000020, 0x00100020, 0x00108000, 0x00000000,
            0x80008000, 0x00008020, 0x80000000, 0x80100020, 0x80108020,
            0x00108000 };

    private static final int[] SP3 = { 0x00000208, 0x08020200, 0x00000000,
            0x08020008, 0x08000200, 0x00000000, 0x00020208, 0x08000200,
            0x00020008, 0x08000008, 0x08000008, 0x00020000, 0x08020208,
            0x00020008, 0x08020000, 0x00000208, 0x08000000, 0x00000008,
            0x08020200, 0x00000200, 0x00020200, 0x08020000, 0x08020008,
            0x00020208, 0x08000208, 0x00020200, 0x00020000, 0x08000208,
            0x00000008, 0x08020208, 0x00000200, 0x08000000, 0x08020200,
            0x08000000, 0x00020008, 0x00000208, 0x00020000, 0x08020200,
            0x08000200, 0x00000000, 0x00000200, 0x00020008, 0x08020208,
            0x08000200, 0x08000008, 0x00000200, 0x00000000, 0x08020008,
            0x08000208, 0x00020000, 0x08000000, 0x08020208, 0x00000008,
            0x00020208, 0x00020200, 0x08000008, 0x08020000, 0x08000208,
            0x00000208, 0x08020000, 0x00020208, 0x00000008, 0x08020008,
            0x00020200 };

    private static final int[] SP4 = { 0x00802001, 0x00002081, 0x00002081,
            0x00000080, 0x00802080, 0x00800081, 0x00800001, 0x00002001,
            0x00000000, 0x00802000, 0x00802000, 0x00802081, 0x00000081,
            0x00000000, 0x00800080, 0x00800001, 0x00000001, 0x00002000,
            0x00800000, 0x00802001, 0x00000080, 0x00800000, 0x00002001,
            0x00002080, 0x00800081, 0x00000001, 0x00002080, 0x00800080,
            0x00002000, 0x00802080, 0x00802081, 0x00000081, 0x00800080,
            0x00800001, 0x00802000, 0x00802081, 0x00000081, 0x00000000,
            0x00000000, 0x00802000, 0x00002080, 0x00800080, 0x00800081,
            0x00000001, 0x00802001, 0x00002081, 0x00002081, 0x00000080,
            0x00802081, 0x00000081, 0x00000001, 0x00002000, 0x00800001,
            0x00002001, 0x00802080, 0x00800081, 0x00002001, 0x00002080,
            0x00800000, 0x00802001, 0x00000080, 0x00800000, 0x00002000,
            0x00802080 };

    private static final int[] SP5 = { 0x00000100, 0x02080100, 0x02080000,
            0x42000100, 0x00080000, 0x00000100, 0x40000000, 0x02080000,
            0x40080100, 0x00080000, 0x02000100, 0x40080100, 0x42000100,
            0x42080000, 0x00080100, 0x40000000, 0x02000000, 0x40080000,
            0x40080000, 0x00000000, 0x40000100, 0x42080100, 0x42080100,
            0x02000100, 0x42080000, 0x40000100, 0x00000000, 0x42000000,
            0x02080100, 0x02000000, 0x42000000, 0x00080100, 0x00080000,
            0x42000100, 0x00000100, 0x02000000, 0x40000000, 0x02080000,
            0x42000100, 0x40080100, 0x02000100, 0x40000000, 0x42080000,
            0x02080100, 0x40080100, 0x00000100, 0x02000000, 0x42080000,
            0x42080100, 0x00080100, 0x42000000, 0x42080100, 0x02080000,
            0x00000000, 0x40080000, 0x42000000, 0x00080100, 0x02000100,
            0x40000100, 0x00080000, 0x00000000, 0x40080000, 0x02080100,
            0x40000100 };

    private static final int[] SP6 = { 0x20000010, 0x20400000, 0x00004000,
            0x20404010, 0x20400000, 0x00000010, 0x20404010, 0x00400000,
            0x20004000, 0x00404010, 0x00400000, 0x20000010, 0x00400010,
            0x20004000, 0x20000000, 0x00004010, 0x00000000, 0x00400010,
            0x20004010, 0x00004000, 0x00404000, 0x20004010, 0x00000010,
            0x20400010, 0x20400010, 0x00000000, 0x00404010, 0x20404000,
            0x00004010, 0x00404000, 0x20404000, 0x20000000, 0x20004000,
            0x00000010, 0x20400010, 0x00404000, 0x20404010, 0x00400000,
            0x00004010, 0x20000010, 0x00400000, 0x20004000, 0x20000000,
            0x00004010, 0x20000010, 0x20404010, 0x00404000, 0x20400000,
            0x00404010, 0x20404000, 0x00000000, 0x20400010, 0x00000010,
            0x00004000, 0x20400000, 0x00404010, 0x00004000, 0x00400010,
            0x20004010, 0x00000000, 0x20404000, 0x20000000, 0x00400010,
            0x20004010 };

    private static final int[] SP7 = { 0x00200000, 0x04200002, 0x04000802,
            0x00000000, 0x00000800, 0x04000802, 0x00200802, 0x04200800,
            0x04200802, 0x00200000, 0x00000000, 0x04000002, 0x00000002,
            0x04000000, 0x04200002, 0x00000802, 0x04000800, 0x00200802,
            0x00200002, 0x04000800, 0x04000002, 0x04200000, 0x04200800,
            0x00200002, 0x04200000, 0x00000800, 0x00000802, 0x04200802,
            0x00200800, 0x00000002, 0x04000000, 0x00200800, 0x04000000,
            0x00200800, 0x00200000, 0x04000802, 0x04000802, 0x04200002,
            0x04200002, 0x00000002, 0x00200002, 0x04000000, 0x04000800,
            0x00200000, 0x04200800, 0x00000802, 0x00200802, 0x04200800,
            0x00000802, 0x04000002, 0x04200802, 0x04200000, 0x00200800,
            0x00000000, 0x00000002, 0x04200802, 0x00000000, 0x00200802,
            0x04200000, 0x00000800, 0x04000002, 0x04000800, 0x00000800,
            0x00200002 };

    private static final int[] SP8 = { 0x10001040, 0x00001000, 0x00040000,
            0x10041040, 0x10000000, 0x10001040, 0x00000040, 0x10000000,
            0x00040040, 0x10040000, 0x10041040, 0x00041000, 0x10041000,
            0x00041040, 0x00001000, 0x00000040, 0x10040000, 0x10000040,
            0x10001000, 0x00001040, 0x00041000, 0x00040040, 0x10040040,
            0x10041000, 0x00001040, 0x00000000, 0x00000000, 0x10040040,
            0x10000040, 0x10001000, 0x00041040, 0x00040000, 0x00041040,
            0x00040000, 0x10041000, 0x00001000, 0x00000040, 0x10040040,
            0x00001000, 0x00041040, 0x10001000, 0x00000040, 0x10000040,
            0x10040000, 0x10040040, 0x10000000, 0x00040000, 0x10001040,
            0x00000000, 0x10041040, 0x00040040, 0x10000040, 0x10040000,
            0x10001000, 0x10001040, 0x00000000, 0x10041040, 0x00041000,
            0x00041000, 0x00001040, 0x00001040, 0x00040040, 0x10000000,
            0x10041000 };

    /**
     * generate an integer based working key based on our secret key and what we
     * processing we are planning to do.
     * 
     * Acknowledgements for this routine go to James Gillogly & Phil Karn.
     * (whoever, and wherever they are!).
     */
    protected int[] generateWorkingKey(boolean encrypting, byte[] key) {
        int[] newKey = new int[32];
        boolean[] pc1m = new boolean[56], pcr = new boolean[56];

        for (int j = 0; j < 56; j++) {
            int l = pc1[j];

            pc1m[j] = ((key[l >>> 3] & bytebit[l & 07]) != 0);
        }

        for (int i = 0; i < 16; i++) {
            int l, m, n;

            if (encrypting) {
                m = i << 1;
            } else {
                m = (15 - i) << 1;
            }

            n = m + 1;
            newKey[m] = newKey[n] = 0;

            for (int j = 0; j < 28; j++) {
                l = j + totrot[i];
                if (l < 28) {
                    pcr[j] = pc1m[l];
                } else {
                    pcr[j] = pc1m[l - 28];
                }
            }

            for (int j = 28; j < 56; j++) {
                l = j + totrot[i];
                if (l < 56) {
                    pcr[j] = pc1m[l];
                } else {
                    pcr[j] = pc1m[l - 28];
                }
            }

            for (int j = 0; j < 24; j++) {
                if (pcr[pc2[j]]) {
                    newKey[m] |= bigbyte[j];
                }

                if (pcr[pc2[j + 24]]) {
                    newKey[n] |= bigbyte[j];
                }
            }
        }

        //
        // store the processed key
        //
        for (int i = 0; i != 32; i += 2) {
            int i1, i2;

            i1 = newKey[i];
            i2 = newKey[i + 1];

            newKey[i] = ((i1 & 0x00fc0000) << 6) | ((i1 & 0x00000fc0) << 10)
                    | ((i2 & 0x00fc0000) >>> 10) | ((i2 & 0x00000fc0) >>> 6);

            newKey[i + 1] = ((i1 & 0x0003f000) << 12)
                    | ((i1 & 0x0000003f) << 16) | ((i2 & 0x0003f000) >>> 4)
                    | (i2 & 0x0000003f);
        }

        return newKey;
    }

    /**
     * the DES engine.
     */
    protected void desFunc(int[] wKey, byte[] in, int inOff, byte[] out,
            int outOff) {
        int work, right, left;

        left = (in[inOff + 0] & 0xff) << 24;
        left |= (in[inOff + 1] & 0xff) << 16;
        left |= (in[inOff + 2] & 0xff) << 8;
        left |= (in[inOff + 3] & 0xff);

        right = (in[inOff + 4] & 0xff) << 24;
        right |= (in[inOff + 5] & 0xff) << 16;
        right |= (in[inOff + 6] & 0xff) << 8;
        right |= (in[inOff + 7] & 0xff);

        work = ((left >>> 4) ^ right) & 0x0f0f0f0f;
        right ^= work;
        left ^= (work << 4);
        work = ((left >>> 16) ^ right) & 0x0000ffff;
        right ^= work;
        left ^= (work << 16);
        work = ((right >>> 2) ^ left) & 0x33333333;
        left ^= work;
        right ^= (work << 2);
        work = ((right >>> 8) ^ left) & 0x00ff00ff;
        left ^= work;
        right ^= (work << 8);
        right = ((right << 1) | ((right >>> 31) & 1)) & 0xffffffff;
        work = (left ^ right) & 0xaaaaaaaa;
        left ^= work;
        right ^= work;
        left = ((left << 1) | ((left >>> 31) & 1)) & 0xffffffff;

        for (int round = 0; round < 8; round++) {
            int fval;

            work = (right << 28) | (right >>> 4);
            work ^= wKey[round * 4 + 0];
            fval = SP7[work & 0x3f];
            fval |= SP5[(work >>> 8) & 0x3f];
            fval |= SP3[(work >>> 16) & 0x3f];
            fval |= SP1[(work >>> 24) & 0x3f];
            work = right ^ wKey[round * 4 + 1];
            fval |= SP8[work & 0x3f];
            fval |= SP6[(work >>> 8) & 0x3f];
            fval |= SP4[(work >>> 16) & 0x3f];
            fval |= SP2[(work >>> 24) & 0x3f];
            left ^= fval;
            work = (left << 28) | (left >>> 4);
            work ^= wKey[round * 4 + 2];
            fval = SP7[work & 0x3f];
            fval |= SP5[(work >>> 8) & 0x3f];
            fval |= SP3[(work >>> 16) & 0x3f];
            fval |= SP1[(work >>> 24) & 0x3f];
            work = left ^ wKey[round * 4 + 3];
            fval |= SP8[work & 0x3f];
            fval |= SP6[(work >>> 8) & 0x3f];
            fval |= SP4[(work >>> 16) & 0x3f];
            fval |= SP2[(work >>> 24) & 0x3f];
            right ^= fval;
        }

        right = (right << 31) | (right >>> 1);
        work = (left ^ right) & 0xaaaaaaaa;
        left ^= work;
        right ^= work;
        left = (left << 31) | (left >>> 1);
        work = ((left >>> 8) ^ right) & 0x00ff00ff;
        right ^= work;
        left ^= (work << 8);
        work = ((left >>> 2) ^ right) & 0x33333333;
        right ^= work;
        left ^= (work << 2);
        work = ((right >>> 16) ^ left) & 0x0000ffff;
        left ^= work;
        right ^= (work << 16);
        work = ((right >>> 4) ^ left) & 0x0f0f0f0f;
        left ^= work;
        right ^= (work << 4);

        out[outOff + 0] = (byte) ((right >>> 24) & 0xff);
        out[outOff + 1] = (byte) ((right >>> 16) & 0xff);
        out[outOff + 2] = (byte) ((right >>> 8) & 0xff);
        out[outOff + 3] = (byte) (right & 0xff);
        out[outOff + 4] = (byte) ((left >>> 24) & 0xff);
        out[outOff + 5] = (byte) ((left >>> 16) & 0xff);
        out[outOff + 6] = (byte) ((left >>> 8) & 0xff);
        out[outOff + 7] = (byte) (left & 0xff);
    }
}
